The invention relates to a toothbrush and in particular to an interdental toothbrush with a detachable brush. The invention further relates to a handle and to a brush, respectively, for an interdental toothbrush.
Some people have retracted gums, which leads to the formation of more or less open interspaces between the necks of adjacent teeth. As people grow old, the gums around the teeth tend to be more and more retracted, thereby exposing more of the necks, which leads to the formation of more open interspaces between the necks of adjacent teeth. A regular toothbrush is limited as to the tooth and gum surfaces that it can reach; in particular it cannot reach into the interspaces between the teeth. Even for people who do not have open interspaces between their teeth, regular toothbrushes are often not satisfactory as to in what extent they reach and clean around the necks of the teeth.
As a result, it is common to provide a small twisted wire brush that can reach into and through these interspaces. Twisted wire brushes are available in various shapes and sizes to accommodate the diverse needs of users, which vary upon the shape and the size of the teeth and the spacing between them. For example, some twisted wire brushes have a conical shape, while others have a cylindrical shape. Similarly, some brushes have relatively large brush and stem diameters, while others have smaller brush and stem diameters.
The brush is usually firmly arranged on one end of a longitudinal handle, concentric or at right angle to the longitudinal axis of the handle.
However, in addition to the different needs of different users, a single user may have relatively large interdental spaces at one place and relatively small interspaces at another place. Thus, it is desirable to provide an interdental brush with a handle that can interchangeably receive and carry different types of brushes.
An example of a interdental toothbrush with a detachable brush is described in U.S. Pat. No. 5,201,091 (Tarrson et al.). The handle has a hinged two-part locking retainer on the end of an elongated handle. The first part of the hinged locking retainer is integral with the handle and the second part is arranged to be folded back and retained adjacent to the first part. The locking retainer has a through hole located in the second part close to the hinge-axis and being arranged to receive the twisted wire forming the stem of the twisted wire brush. When the user is about to use the brush, the stem of the brush is inserted in the through hole and the portion of the stem extending past the hole is received in a slot in said first part of the retainer. Thereafter the second part of the retainer is folded back, thereby bending the stem of the brush. The bending of the stem of the brush prevents the brush from being retracted or further inserted when the interdental brush is used.
However, the bending of the stem is permanent and the brush can only be attached to the handle once. Thus, the user cannot use this type of interdental brush if there is a need for more than one size or shape of the brush.
Furthermore, it is difficult to place and hold the twisted wire stem of the brush in the correct position, before and while folding back the second part of the hinged locking retainer. This drawback is present even for young people with good eyesight and well functioning fingers, and is further pronounced since it is especially elderly people that need interdental brushes. The elderly people may have stiff or weak hands, impaired eyesight or other handicaps that limit their ability to manipulate the handle and the brush.
Another example of a interdental toothbrush with a detachable brush is described in U.S. Pat. No. 5,758,382 (Maekawa et al.). The handle has a hinged two-part locking retainer on the end of an elongated handle. The first part of the hinged locking retainer are integral with the handle and the second part is arranged to be folded back and retained adjacent the first part. The first part has two sidewalls arranged to extend on both sides of the second part in the folded position of the locking retainer. One of the sidewalls has a V-shaped gap for receiving the twisted wire stem of the brush. As the locking retainer is closed, the twisted wire stem is frictionally captured and clamped between the first and second part of the hinged locking retainer. Thus, it is the friction that retains the brush in the handle when the interdental brush is used. In order for the friction to be high enough, the locking retainer must exert a clamping force of high magnitude, which in turn implies that the locking retainer must be rigid and therefore also relatively large. The high magnitude of the clamping force also implies that the force needed to close the locking retainer is of considerable magnitude, which may be a problem, especially for older people.
In a preferred embodiment of the prior art the first part of the locking retainer has an indentation between the two opposing sidewalls and the second part has a protrusion in communication with the indentation. The indentation and protrusion interact and causes the twisted wire stem to be bent and locked in place when the locking retainer is closed. Thus, the user cannot use this type of interdental brush if there is a need for more than one size or shape of the brush.
The object of the invention is to solve the above mentioned problems related to the known interdental brushes.
A particular object of the invention is to provide an interdental brush by which a detachable brush can be detached and reattached several times.
The objects of the invention has been achieved in accordance with the invention by a detachable brush, a fastening portion for a detachable brush, a toothbrush retainer and a toothbrush.
In accordance with the invention, the object is achieved by a detachable brush comprising a brush portion and a fastening portion that extends along a first axis. The detachable brush is further characterised in that the fastening portion comprises a first surface, whose normal has at least a component in a first direction along said first axis, and a second surface, whose normal has at least a component in a second direction, opposite to the first direction, along said first axis.
The two surfaces directed in (at least partly) two directions along the first axis provides efficient retaining surfaces such that the detachable brush can be retained and prevented from being displaced back or forth along its first axis.
According to a preferred embodiment of the detachable brush, the fastening portion comprises a first central portion, with a first cross-section area, and two end portions, one on each side of the central portion along said first axis, with a second and a third cross-section area, respectively. The first cross-section area is different from the second and third cross-section areas, and said surfaces form junctions between the central portion and the end portions. This is a simple and robust way of providing the fastening portion with the necessary retaining surfaces. Furthermore, this embodiment makes the detachable brush easy to handle.
According to a preferred embodiment, the first surface is oriented such that its normal is directed along said first axis and that it forms a step that is perpendicular to said first axis. This step-shape makes it easy to place the detachable brush correctly on the toothbrush retainer unit. The step provides an unambiguous indication for the user, whether the detachable brush is correctly placed or not.
In the same manner it is preferred that also the second surface is oriented such that its normal is directed along said first axis and that it forms a step that is perpendicular to said first axis.
In accordance with another preferred embodiment, the first cross-section area is smaller than each of the second and the third cross-section areas. This is also related to the easiness of placing the brush and the user""s feeling of correct placement or not. An item shaped this way is easy to place on a corresponding surface and the outer portions (the second and third portion) keeps the item in place.
It is preferred that the central portion has an extension along said first axis that exceeds the extension of each end portion along said first axis. This makes the detachable brush stable when received and carried by the toothbrush retainer.
The fastening portion of the detachable brush can be manufactured separately from the brush, which preferable is a twisted wire brush of known type, and then put together with the brush. Thus, in order to be used as a fastening portion for a detachable brush, the separate fastening portion presents the problem-solving features mentioned above in connection with the detachable brush.
In accordance with the invention, the object is also achieved by a toothbrush retainer comprising a first retainer portion connected to a second retainer portion, wherein the second retainer portion is foldable, relative to the first retainer portion, about a hinge axis, wherein the first and second retainer portions, when folded in a first, closed position, between them form an interspace, by which the retainer portions are adapted to retain a detachable brush. The tooth brush retainer is characterised in that the retainer portions, in order to retain a detachable brush, each comprise a first surface being angled in a first direction such that a normal of the first surface has at least a component in a first direction along said hinge axis, and a second surface being angled in a second direction such that a normal of the second surface has at least a component in a second direction, opposite to the first direction, along said hinge axis.
The two surfaces directed in (at least partly) two directions along the first axis provides efficient retaining surfaces such that the retainer portions can retain and prevent a detachable brush from being displaced back or forth along its first axis. Displacement of a detachable brush in other directions (forming an angle to said first axis) is prevented by the fact that the retainer portions between them form an interspace in which the detachable brush is adapted to be placed.
According to a preferred embodiment the retainer is connected to, and preferably integrated with, a longitudinal toothbrush handle in order to make the brush easier to use.
In the same manner as to the fastening portion, said first surface of the toothbrush retainer is preferably oriented such that its normal is directed along said hinge axis and that it forms a step that is perpendicular to said hinge axis.
Likewise the second surface is preferably oriented such that its normal is directed along said hinge axis and that it forms a step that is perpendicular to said hinge axis.
According to a preferred embodiment, the retainer portions are flat along the hinge axis and said first and second surfaces are formed by the side surfaces of the retainer portions. This shape of the retainer portions is easy to manufacture, it is easy to place a detachable brush onto such a shape, the detachable brush easily engages said retaining surfaces and the user feels at once if the detachable brush is placed correctly or not.
It is preferred that the retainer portions are angled an angle xcex1 relative to the handle about an axis that is normal to a geometric plane defined by the handle and the hinge axis. A preferred value of the angle xcex1 is about 10xc2x0. In this way the brush is inclined in respect of the handle, which makes it easier to reach interspaces further back in the mouth.
According to a preferred embodiment, the retainer portions and the interspace formed between them are symmetric along the hinge axis in respect of a plane that is centrally placed and is a normal plane to said hinge axis. In this way a detachable brush can be placed in the retainer in either direction, and the inclination of the brush relative to the handle can be utilised to its full extent. The user can choose between to different inclinations of the brush in respect of the handle, e.g. left-handed and right-handed people might have different needs, and the need of one user may vary as to brushing different teeth in different parts of the mouth.
In accordance with the invention, the object is also achieved by a toothbrush comprising a detachable brush, with a brush portion and a fastening portion that extends along a first axis, and a handle with a first retainer portion connected to a second retainer portion, wherein the second retainer portion is foldable, relative to the first retainer portion, about a hinge axis, wherein the first and second retainer portions, when folded in a first, closed position, between them form an interspace in which the detachable brush is retained. The toothbrush is characterised in that the retainer portions, in order to retain a detachable brush, comprise a first surface being angled in a first direction such that a normal of the first surface has at least a component in a first direction along said hinge axis, and a second surface being angled in a second direction such that a normal of the second surface has at least a component in a second direction, opposite to the first direction, along said hinge axis. Furthermore, the fastening portion of the detachable brush, in order to be retained, comprises a first surface being angled in a first direction such that a normal of the first surface has at least a component in a first direction along said first axis, and a second surface being angled in a second direction such that a normal of the second surface has at least a component in a second direction, opposite to the first direction, along said first axis. The brush is supported by the retainer portions such that the first axis and the hinge axis are essentially parallel, and preferably coincide, and in the first surface of the fastening portion and the second surface of the retainer portions face and abut or substantially abut each other, and the second surface of the fastening portion and the first surface of the retainer portions face and abut or substantially abut each other.
In this way the detachable brush is securely carried by the handle and the user can use a small brush with a large easy-to-grip handle. It is easy to place, and replace, the brush between the retainer portions. The brushes are not damaged by the insertion or clamping between the retainer portions. Thus, one brush can be inserted several times with ease. The consequence is that people who need different kinds of brushes at the same time can easily change brushes whenever needed.